Open vs closed surgical exposure of palatally displaced canines: a comparison of clinical and patient-reported outcomes-a multicentre, randomized controlled trial

Eur J Orthod. 2021 Oct 4;43(5):487-497. doi: 10.1093/ejo/cjab015.


Objectives: To compare treatment time, patients' perceptions during orthodontic treatment, dental fear and side effects, between open and closed surgical exposures in patients with palatally displaced canines (PDCs).

Trial design: Multicentre, randomized controlled trial, with random 1:1 allocation of two parallel groups.

Materials and methods: One hundred and twenty patients from three different orthodontic centres were randomized into one of the two intervention arms, open or closed surgical exposure. Both techniques had mucoperiosteal flaps raised and bone removed above the PDCs. In open exposure, tissue was removed above the canine, and glass ionomer - reaching above soft tissue - was built on the crown. The canine was then left to erupt spontaneously, prior to orthodontic alignment. At closed exposure, a chain was bonded to the canine and orthodontic traction was applied under the mucosa until eruption. Orthodontic alignment of the canines was undertaken after eruption into the oral cavity, with fixed appliances in both groups. All participants were treated according to intention to treat (ITT).

Blinding: Due to the nature of this trial, only outcome assessors could be blinded to the intervention group.

Results: One hundred and seventeen patients completed the trial. All PDCs were successfully aligned. Total treatment time was equal in the two techniques, mean difference -0.1 months (95% CI -3.2 to 2.9, P = 0.93). The closed group experienced more pain and discomfort during the active orthodontic traction. Dental fear, root resorption and periodontal status did not show any clinically significant differences between the groups.

Generalizability: Results of this randomized controlled trial (RCT) can be generalized only to a similar population aged 9-16 years, if exclusion criteria are met.

Conclusion: The closed exposure group experienced more pain and discomfort mostly during active orthodontic traction. All other studied outcomes were similar between the two exposure groups.

Clinical trial registration:, ID: NCT02186548 and, ID: 127201.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cuspid / diagnostic imaging
  • Cuspid / surgery
  • Humans
  • Patient Reported Outcome Measures
  • Tooth Crown
  • Tooth Eruption
  • Tooth Eruption, Ectopic* / surgery

Associated data